Leather conditioning cutter



J. H. KELLY 2,429,822

LEATHER CONDITIONING CUTTER 2 Sheefcs-Sheet 1 Filed Aug. 3, 1944 I "i la r /VVENTOE.' Johwh Keur Hrroe/VEY Oct. 28, 1947. J. H. KELLY LEATHER CONDITIONING CUTTER Filed Aug. 5,. 1944 2 Sheets-Sheet 2 r t u;

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Aww www Patented Oct. 28, 1947 UNITEDA STATESI PATENT CFFICE 2,429,822

v LEATHER coNDrrroNmG ou'r'rER John n. Keuy, Pittsburgh, Pa Application August 3, 1944, Serial No. 547,954

This invention relates generally to the art of conditioning surfaces of leather and similar material preparatory to the application of an adhesive for attaching the leather to another body and more particularly to the method of cutting and the form of thev cutter for producing the conditioned surface. This invention is advantageous for conditioning the surface on the flesh side of tread-soles.. preparatory to cementing them to shoes. It is equally advantageous in preparing the adjacent lapped surfaces of a belt joint and other applications where leather is to be cemented to another body.

In the shoe manufacturing and shoe repairing industries various methods are employed to score the flesh fibers and roughening the attaching face of a leather sole. The two methods commonly used employ a grooving cutter or 4a wire wheel brush. Both of these tools have their singular limitations which are objectionable.

In operation the grooving cutters .will cut into the leather to the depth of the teeth formed on the cutter, leaving untouched they original loose fibrous flesh surface between the grooves. This untouched flesh surface represents the ridges deflning the grooves and it comes into direct contact with the attaching face of the shoe. Even though the leather and the cement are of the best quality the joint will fail because flesh fibers are loose and break away, not being able to produce a good cemented ljoint. If the leather is held against the cutter for a sufficient length of time to remove the top flesh fibers the teeth of the cutter burnish the leather in the grooves. The cement cannot penetrate this glazed leather surface and a joint made with such 9, conditioned surface fails. y

It is believed that the Wire Vbrush produces a superior conditioned surface to that of the grooving cutter. Howeverit does notremove all of the flesh fibers, whichv is objectionable. Again the wire brush requires a considerably longer time to produce a. conditioned surface that is suitable for cement. The wire bristles readily break off due to continuous flexing, causing rapid wear and frequent replacement of the brush. Furthermore, transparent shields Vmust be provided to protect the operator from the flying pieces of broken wire. Thus the time required to condition a leather surface and the frequent replacement of the Wire brush make it economically undesirable, even though-,it is considered to produce a superior conditioned surface compared to that made by'the grooving cutter.

The principal object of inisinvention is thev provision of a cutter and cutting process for quickly and economically removing all of the flesh fibers, to produce a conditioned leather surface for receiving an adhesive cement. v

Another object is the production of a conditioned leather surface having a nap of close bers.

Another object is the provision of a cutter for producing a grooved conditioned surface that is open or porous and is free of esh fibers.

Another object is the provision of a cutter having a series of teeth disposed in an aligned helical path around the perimeter of the cutter.

Another object is the provision of a cutter having an annular series of teeth around the perimetral surface of thecutter with a cutting profile of adjacent teeth in the same series being offset from one another.

Another object is the provision of a cutter having a set of teeth disposed in a helical path around the perimeter of the cutter and an adjacent set of teeth disposed in a helical path of the opposite hand.

An'other object is the provision of a cutter having a plurality of 'sets of uniformly spaced projections disposed about the periphery of the cutter with the .projections of adjacent sets being offset radially and teeth on projection of each set being disposed in a helical path around the perimeter of the cutter with the teeth on the adjacent set of projections being disposed in a helical path of opposite hand. Each set of uniformly spaced projection sections being a separate member. y

Other objects and advantages appear in the following specification and claims. i

A practical embodiment illustrating the principles of the invention is shown in thev accompanying drawing wherein;

Fig. 1 is a view in side elevation of the cutter.

Fig. 2 is a perspective viewshowing the outer end of the cutter.

Fig. 3 is an expioded view of the cutter parts.

Fig. 4 is a diagrammatic view of the teeth tracks of the four cutter sections.

Fig. 5 is a side elevation of a cutter section having a keyway.

Fig. 6 is an enlarged diagrammatic view illustrating the relative position of the cutting teeth and the method of producing the conditioned surface.

Fig. '7 is a plan view of a shoe sole having a conditioned surface.

Fig. 8 is an enlarged view showing the conditioned surface of the sole.

Referring to the drawings, the cutter I is preferably made in a, plurality, such as four sections or blanks I, 2, 3 and 4 to facilitate in forming the teeth ln the perimetral surface thereof. These four sections materially simplify manufacture of the cutter as it is more diiilcult and more expensive to grind a single blank of the same character. The cutter sections I, 2, 3 and 4 are each provided with an axial bore to permit them to be assembled together on the outer section II of the shaft I2 against the shoulder I3.- 'I'he shaft I2 is arranged to be journaled in a machine and driven by suitable means such as a motor. A machine of this character is disclosed in U. S. Patent No. 2,287,999.` The outer or free end II of the shaft is provided with an axially threaded hole I4 to receive the clamping bolt I5 which carries the clamping washer I3. The total width of the four .cutter sections are slightly greater than the length of the outer section II of the shaft I2 to permit the clamping bolt I5 to firmly hold the cutter sections in assembled relation on the shaft.

In the structure shown each cutter section is provided with an annular series of ten projections, I1, to produce a blank shape that is similar to that of a ratchet gear. One or more teeth I8 are formed in the perimetral surface of the blank. -The cutting profile of each -tooth lies in the face of the projection I1 which is disposed substantially radial but'preferably slopes toward the back face 2| of the projection and the tip or apex lags the root of the tooth proiile which gives the teeth a negative rake.

The back 2l of each projection slopes rearwardly toward the followinglprojection. In the structure in Fig. 6 the projections I'I are shaped more like the teeth oi.' a sprocket and the faces 22 and 23 on both sides of each projection have the same slope and are tangent to a common imaginary cylinder. Thus both faces 22 and 23 provide cutting profiles of the teeth I8 and the cutter is reversible in operation. Y

The flutes or gaps 24 between the projections I1 are preferably wide to permit the escape of the leather cuttings. The cutter disclosed herein provides ample space for this purpose and rarely requires cleaning.

In view of the fact that a considerable space 24 is provided between adjacent projections of each cutter section the individual cutter sections would not provide continuous support or bearing surface for the leather being conditioned. This difficulty is overcome by providing two or more cutter sections and so disposing the projections of one section relative to the other that continuous bearing or support of the leather is obtained. This is an important object of this invention and is shown in Fig. 2 wherein the support of the leather surface is shifted from projections of different cutter sections in the sequence of I, 3, 2, 4

to one another and if the inner sections 2 and 3 are positioned with their cutting faces aligned and in the proper numerical sequence the assembly will be proper, as shown. This is an important object of this invention. The sockets 25 and 29 and the holes 21 and 28 must each be properly located with reference to the projections and cutting faces of their respective sections to provide surface support of the leather by the projections of the cutter sections in the desired sequence. The sequence of the cutter sections in Figs. 1 and 2 are I, 2, 3 and 4, Yhowever the projection sequence in supporting the leather surface is I, 3, 2 and 4 as demonstrated by the tracks shown in Fig. 4.

The tracks shown in Fig. 4 are the marks made by the ridges of the teeth of the assembled cutter when rolled across the page and the first, second, third and fourth series of tracks are formed by cutter sections I, 2, 3 and 4 respectively, and when read in the direction of the arrow the sequence of the engagement of the surface bythe teeth are in the order of sections I. 3, 2, 4, which is continuously repeated.

In the/cutter shown it is intended that as the trailing ends of the teeth of one projection are about to leave, the leading ends of the teeth of the next projection are about to enter the leather surface. These projections may be made suinciently long to cause the teeth of successive projections to overlap in their engagement with each other as shown in Fig. 4, but is not believed to be desirable to make the projections less in length than that shown in Figs. 1 and 2 because there would not be sufficient material to permit grinding of the profiles when the cutter is sharpened.

The cutter section 30 illustrated in Fig. 5 is provided with a keyway 3| to receive the key 32 carried by the shaft 33 of a leather surface conditioning machine. The keyways 3| of the respective cutter sections are preferably disposed to provide the same result as by the pin 25. Howacross the perimeter of the cutter as it is rotated.

When assembled. as shown in Figs. 1 and 2, the cutter sections may be maintained in their relative positions by employing the pin 25 as shown in Fig. 3 which enters the socket 26 in the inner side of the cutter section I and passes through the holes 21 and 28 in sections 2 and 3 and enters the socket 29 of the inner side of the section 4. The sockets 26 and 23 admit the ends of the pin 25 but do not permit it to pass therethrough. This construction is advantageous because the cutter can only be assembled with the sections I and 4 on the outside and in the proper relation ever the keyways provide a positive drive from theshaft whereas the structure shown in Fig, 3 relies upon clamping friction as shown in the drawings.

The thickness of the cutter sections together with the size of the teeth are selected to provide at least two teeth on each projection. The diagrammatic view, Fig. 6, shows a single projection I1 having two teeth 35 and 36 in spaced relation on the perimetral surface of the projection, and thev tracks of these teeth are similarly designated in Fig. 4. Tooth 38 is the outer tooth on the projection. There are ten projection sections in the section blank, and these teeth are matched or duplicated on the diametrically opposite projection and are indicated by the reference numerals 35' and 36'. The cutting profile of the teeth on the intermediate projections are oiset relative to these duplicated pairs of teeth. Thus the teeth of each projection match or duplicate the teeth of the diametrically opposite projection.

The oiset relation of the teeth in consecutive projections is indicated in Fig. 6 by the outer tooth on each of a consecutive series of five pro- Jections in the same plane.

Thus the teeth 31, 38, 33 and 40, are disposed circumferentially about the cutter and lle between the planes of the teeth 35 and 36 of Fig. 6, and each indicate the outer tooth on each of a consecutive series of projections between the diametrically disposed projections carrying the teeth 36 and 3B in cutter section I. The tracks of these teeth shown in Fig. 4 are designated by the same reference numeral.

There are ten projections on each cutter sec-- tion and the offset relation is repeated in the second consecutive series and designated at 36'., 31', 38. 39 and40' in Fig. 4. Since the teeth on the projections are in pairs, the second tooth of each succeeding projection, which is uniformly spaced from the rst tooth, is also offset relative to the tooth 35 in the same consecutive order. In Fig. 6 a series of teethare shown in the grooves 46 cut in the leather body 4 I.

Leather is divided into three layers, the grain 42, the close fibers 43 and the loose flesh fibers 44. The consecutive series of teeth, 36 to 40, each cut their own groove in the leather and their relative proximity due tothe offset of the consecutive teeth determines the depth of the cut or the amount of leather removed from one or more layers and the second consecutive series of teeth, 36' to 40', will follow in the corresponding grooves when the cutter has revolved 180`degrees to `per form the same function.

In Fig. 6 the teeth are cutting into the close fiber layer 43 of the leather and the grain layer 42 has vnot been touched but the flesh layer 44 is totally removed by the sides or flanks of the cutting profiles of the teeth, as the limit of the crests 4-5 of the grooves in the leather are determined by the degree of oilset'in the consecutive series of teeth. The crest 45 of rthe grooves lie below the flesh layer 44. Thusthe proximity of the grooves determines the depth and width of the grooves. If the offset of the teeth is less than that shown in Fig. 6 the grooves 46 would not be as deep nor as wide as that shown, but would be smaller and closer together.

Thus by regulating the degree of oifset in a consecutive series of teeth the depth -of the grooves and the amount of surface removed from the Aleather may be accurately regulated. `This is an important object of this invention.

It follows that a cutter having a consecutive series of teeth which are offset relative to each other will locate the crests of the grooves of the conditioned leather surface below the loose fibrous flesh layer in the leather thereby insuring an ideal surface for receiving a cement. The loose flesh fibers break away easily and do not form a good cementing surface. The close bers are stronger or tougher and aid in producing a good cementing surface. Thus a properly designed cutter will remove all of the flesh layer and none of the crest 45 will have flesh liber. 1

In the cutters now in general use, where the teeth on consecutive projections are in circular alignment, the toothed perimetral surface compresses the flesh fibers in the crests of the grooves formed when the teeth have cut to their full depth, and they are always present on the conditioned surface. The consecutive teeth following inthe same groove compress the fibers in both the flesh and close liber layers. This continued compression causes the grooved surface to be burnished and hard. Such a surface shines and the porosity is materially reduced, which is undesirable since the cement has difficulty in making a bond.

The cutter comprising thisinvention will not burnish the leather surface. In the forms shown there are only two teeth in each cutter section that follow in the same groove and the offset in the teeth cause the side profiles to cut off the fibers and notl burnish or burn the surface. This surface is open and porous regardless of the depth of cut or the amount of leather removed. This is an important advantage of this invention.

An offset between the'cutting profiles ci.' adjacent teeth in an annular series of teeth may l be produced by forming the teeth from an interrupted thread. The cutting profile of each tooth formed from an interrupted thread is offset from the cutting profiles of adjacent teeth because of the pitch of the thread and the number of in- 10 terrupted portions of the thread that are formed on a cutter blank of predetermined diameter. The cutting or leading profile of a tooth formed from an interrupted thread is offset from its trailing profile as well as being offset from the leading or trailing profiles of adjacent teeth.

The interrupted thread forming each tooth section in a. series has an extended crest and these crests of teeth lie in a common cylinder disposed concentrically of the axis of theblank.

If the teeth'have a uniform pitch and they are all lformed from right hand threads, the thrust produced by the helix would throw or push the leather laterally from the cutter. Thus it is desirable to place cutter sections in an assembly of sections which have teeth formedfrom threads of the opposite hand or right and left hand threads. As shown in Figs. 1, 4 and 5 the teeth of cutter sections I and 3 are formed from left hand threads and the teeth of cutter sections 2 and 4 are formed from right hand threads. The only difference between cutter sections I and 3 and the cutter sections 2 and 4 is the location of the keyways 3l or the holes for receiving the locking pin 25. The selection of the relative positions of the cutter sections as shown was found to provide an exceptionally good conditioned surface which.is illustrated in Fig. '7, wherein the flesh side of the sole 4I is shown.

This cutter section arrangement produces the 40 cutter tracks shown in Fig. 4. In Fig. 4 it will be noted that the teeth 35 and 36 on the ilrst projection of the cutter section I are followed by the teeth 48 and 49 of the rst projection of cutter section 3. These two pairs of teeth are formed from a left hand thread or helix and since they follow in succession when engaging the leather surface they would normally move the leather body laterally of the cutting path and toward the rst cutter section. If this lateral 50 thrust is continued the leather body would be ejected axially of the cutter. However, the leather is then engaged by the teeth v5t) and 5| of the cutter section 2 and the teeth 52 and 53 of the cutter section 4 in succession and these 55 two pairs of teeth are formed from a right hand thread or helix which vproduces a lateral thrust 'in the opposite direction tending to maintain the leather body in its original position,

This action of oppositely directed thrusts tends to move the leather body back and forth or vibrate laterally relative to the cutting path or axially of the cutter ten times to each revolution to the cutter. If the leather body is held firmly by hand or by a soft rubber back-up or feed pressure roll, such as disclosed in Patent 2,287,999, this lateral thrust is taken by the sides' of the grooves 46, causing the threads of the cutter to plow up the close bers to produce a nap 54 of the close fibers on the conditioned surface v 55 of the leather sole 4I as shown in Fig. 7.

The cutter moves up the left side of the sole as shown in Fig. 'I and ydown the right. It is traveling at a much faster rate of speed than the feed or controlled movement of the leather but in the same direction as that of the leather.

4 leather and if rubbed the opposite direction it will be ruifed up. The nap is shorterwhen the crests of the teeth of the cutter lie in circular planes normal to the axis of the cutter or when the teeth are formed from helical threads and havel been sharpened to such a degree that the lateral thrust is no longer effective in producing a plowing action. However the longer nap produced by the plowing action o1' the helically extended teeth is preferable as it provides a better surface for receiving cement joint. i

The pitch of the threads determines the offset of the teeth and dimensions of the grooves. If

` and bonding the the pitch of a double leadlthread is greater than r twelve threads per inch no visible groove will be formed by the cutter shown which is approximately two inches in diameter. If the grooves are present the nap or character of the surface vobliterates them to the naked eye. When twenty-eight threads per inch are employed to form the cutting teeth ther cutting action is very smooth and the leather surface is smooth with a fine short nap. Such a cutter is superior to a continuous tooth across the face of the cutter as the latter literally seizes and pounds the leather tearing the fibers apart. On the other hand, the cutter of this invention provides a shearing action that produces a clean cut surface on the leather. Such a surface is good where the leather to be bonded is very thin, but for shoe soles and the like it is preferable to have grooves with a villorus surface to receive the cement in the extended porous surface of the grooves.

In the structure shown the pitch is four threads per inch with a double lead thread. A single lead thread places all of the cutting action on one profile. This -is remedied by providing two threads for each projection. With the pitch of four threads per inch and a double lead thread on a two inch cutter, the firstv tooth has the same helix as the second tooth on the second half of the cutter. Thus in Fig. 4 teeth 36 to 40 lie in the same helical path and are in alignment with the tooth 35 and its annular series on the second half of the cutter. This is brought out in Fig. 4, Vwherein the annular series starting with tooth 36 on cutter section I- is in alignment with the second annular series commencing with tooth 35', and the latter series is in alignment with tooth 48, which is the first annular series, on section 3, etc.

It therefore follows that the teeth of the cutter shown produce forty finite grooves in the leather surfaced when cutting the full extent of its cutting face, which is approximately one inch.

I claim:

1. A cutter for conditioning the surface of a material, comprising a shaft, a pair of cylindrical blanks arranged for rotation with the shaft, and an annular series of teeth disposed circumferentially of each blank, the individual teeth of each series being offset relative to the adjacent teeth of the same series and the consecutive teeth of one blank being offset in an opposite direction than the consecutive teeth on the other blank.

2. A cutter for conditioning thesurface of a material, comprising a shaft. a pair of cylindrical blanks arranged for rotation with the shaft,

and an annular series of teeth disposed circumferentially of each blank, the individual teeth of each series being offset relative to the adjacent teeth of the same series and the individual teeth of one series being staggered relative to the individual teeth of the other series.

3. Arcutter for conditioning the surface of a material, comprising a shaft, a Pair of cylindrical blanks arranged for rotation with the shaft, and an interrupted thread disposed about the circumference of each blank to provide an annular series of cutting teeth. the individual teeth of each series being offset relative to the adjacent teeth-of the same series and the consecutive teeth of one blank being offset in an opposite direction than the consecutive teeth of the other blank. v

4. In a cutter for conditioning the surface of a material, the ycombination of a cylindrical blank arranged for rotation, an interrupted thread having its crests extending in a common cylinder and disposed about the circumference of the blank to provide an annular series of cutting teeth.

5. In a cutter for conditioning the surface of a material, the combination of a cylindrical blank arranged for rotation, an annular series of teeth disposed in spaced relation about the circumference of'the blank, said teeth having extended crests in a common cylinder and having a leading and a trailing profile. the profiles of adjacent teeth in the series and the profiles of eachtooth being offset relative to one another.

6. In a cutter for conditioning the surface of a material, the combination 0f a cylindrical blank arranged for rotation, a plurality of interrupted parallel threads having their crests extending in a common cylinder and disposed about the circumference of the blank to provide a plurality of annular series of cutting teeth.v

7. In a cutter for conditioning the surface of a material, the combination of a shaft. a plurality of cylindrical blanks arranged for rotation 'with the shaft, an interrupted thread disposed about the circumference of each blank to provide an annular series of cutting teeth, the teeth of selected blanks following a right hand helix and the teeth of the other blanks following a helix of opposite hand. Y

8. In a cutter for conditioning the surface of a material, the combination of ablank arranged for rotation, an annular series of spaced radial projections on said blank, `and an annular series of teeth on said projections, the ridges of the teeth lying in a common cylinder and the individual teeth on each projection being offset relative to the teeth on adjacent projections. y

9.v In a cutter for conditioning the surface of a material, the combination for rotation, projections on said blank, and an`annulai` series of teeth on said projections, thecuttlng profiles of said teeth having a negative rake and thev ridgesof .the teeth lying in a common cylinder and the individual teeth on each projection being offset relative to the teeth on adjacent projections.

10. In a cutter for conditioning the surface of a, material, the combination of agtlank arranged for rotation, an annular seriegefspaced radial projections on said blank, each projection having an arcuate surface, said'arcuate surfaces extending in a common cylinder concentric with the blank, a face at each end of the arcuate surface on each projection, and an annular series of teeth extending from one face across the arcuate surof a blank arrangedy an annular series of spaced radial face to the other face of each projection to provide cutting profiles in each faceand with their crests all lying in the common cylinder, the cutting profiles of the teeth in the faces of adjacent projections being oiset relative to one another.

11. In a cutter for conditioning the surface of a material, the combination of a blank arranged for rotation, an annular series of spaced radial projections on said blank, each projection having an arcuate surface, said arcuate surfaces extending in a common cylinder concentric With the blank, a face at each end of the arcuate surface on each projection, and an annular series of teeth extending fromv one face across the arcuate surface to the other face of each projection to provide cutting proles in each face, and with their crests all lying in the common cylinder, the cutting profiles of the teeth in adjacent faces and in the -faces of each projection being oiset relative to one another.

12. In a cutter for conditioning the surface of a material, the combination of a shaft, a plurality of blanks arranged for rotation with the shaft, a plurality of annular series of spaced radial projections on each blank, each projection having an arcuate surface, the arcuate surfaces of each blank extending in a common cylinder concentric with the shaft, and a section of a plurality of parallel interrupted threads on the arcuate surface of each of said projections to provide a plurality of annular series of cutting teeth on each blank with their crests all lying in the common cylinder, the threads on one blank being righthand and the threads on the other blank being left-hand. 4

13. In a multiple disc cutter the combination of a. plurality of discs arranged -to be mounted in nested relation for rotation, said discs having an annular series of spaced radial projections with arcuate surfaces and an annular series of teeth on the arcuate surfaces of the projections, and means to interlock the discs to alternate the projections in staggered relation.

14. In a multiple disc cutter the combination of a plurality o1 discs arranged to be mounted in nested relation for rotation, said discs having an equal number of annularly spaced radial projections with arcuate surfaces and an annular series of teeth on the arcuate surfaces of the projections,

and means to interlock the discs :to alternate the projections in a predetermined staggered relation to shift the cutting action to each disc in a repeated sequence.

15. The structure of claim 13 characterized in that the annular series of teeth on selected discs are in the form of right and left hand interrupted threads.

JOHN H. KELLY.

REFERENCES crran The following references are of record in the ille of this patent:

UNITED STATES PATENTS 

